Giant super-rats that could become as big as cows are spreading across Britain at an “alarming” rate, scientists have warned.

And the mutant beasts are immune from extermination by all available poisons.

“Given enough time, rats could probably grow to be at least as large as the capybara, the world’s largest rodent, that lives today, that can reach 80 kilos ”

Dr Jan Zalasiewicz, Leicester University scientist

A shock new study has confirmed a UK plague, first revealed in the Daily Star, does exist with an estimated 70million of the new breed now in the UK.

Experts working for ITV1’s Tonight show, say that they will outnumber humans two-to-one by the end of the year, when the population will hit 120m.

Another study warned the vermin could become as huge as cows if they continue to evolve.

Families in Kent, Liverpool and other parts of the country have already reported rats as big as cats and foxes.

Leicester University scientist Dr Jan Zalasiewicz said: “Given enough time, rats could probably grow to be at least as large as the capybara, the world’s largest rodent, that lives today, that can reach 80 kilos.”

Experts from Huddersfield University, West Yorks, were stunned to find the mega-rodents were ­resistant to traditional rat-killing substances.

Professor Dr Dougie Clarke warned: “I think people should be concerned about these resistant rats because of public health concerns.

“They carry disease and various other bacteria and viruses and they also damage buildings, while costing billions of pounds of damage worldwide.